Over on Instagram, I shared some of my salsa making process yesterday, with a disclaimer that it's the riskiest water bath canned product to make and you need to make sure you follow the directions.

I got a few responses that indicated that was helpful and sometimes new info.

With more people staying home, gardening, and now canning, there are a lot of newbie folks "putting up" food this summer. Further evidenced by the shortage of canning lids and/or jars in many areas.

I'm a little concerned, because there is a lot of bad canning advice out there.

Particularly on food blogs. I want to scream when I see a comment on a recipe for a soup or sauce or salsa asking, "can I can this?" and the author, who may have never canned a thing in their life, says, "Sure why not?"

PEOPLE DIE FROM EATING IMPROPERLY CANNED FOOD.

Water bath canning is a science, not an art. Each recipe is developed to achieve a safe pH level and density, so when heated in properly sterilized jars they will kill dangerous bacteria (like the one that causes botulism) and prevent more from forming.

Jams are the safest, because the high sugar content serves this purpose. Pickled items are also generally safe, because they are bathed in acidic vinegar. But even then, what goes in the jar matters. Must be washed and/or peeled, minimizing low-acid vegetables.

Tomato-only products like sauce, diced, and crushed are a little more difficult (peeling is a must) and slightly more dangerous, but they're naturally acidic and recipes call for lemon juice to be added for additional safety.

When you start combining multiple vegetables, fruits, and herbs in a jar, things get more complicated. You're introducing more pH variability. The proper ratios are a must.

Like salsa. It's the highest risk food you can waterbath can. But it can be done safely.

Salsa combines acidic foods like tomatoes and vinegar with low-acid foods like onions, garlic, peppers, and sometimes fresh herbs. Tomatoes are always the largest portion of the recipe. Properly tested recipes develop a ratio of low-acid to high acid that is acceptable.

For these recipes, measuring is of the utmost importance. You can't add extra onions or peppers, or skimp on the tomatoes, or you'll risk throwing off the pH balance. Leaving out liquid in the recipe increases the density, which means heat may not penetrate the entire jar.

Lab testing verifies safety. The funding for these labs has been decreasing for years. It's possible your local extension office used to do it, but probably not any more. The National Center for Home Food Preservation (NCHFP) at the University of Georgia is my go-to source.

The NCHFP is an excellent source of reliable, up-to-date information on canning techniques and approved recipes.
https://nchfp.uga.edu/ 

I'm sure your grandma is a lovely lady, but don't trust her hand-written canning recipe from the 1960's. Science has evolved since then.

There are only a few other reliable sources for canning recipes, in my opinion.

The canning companies themselves (e.g., Ball) have recipes on their websites and publish cookbooks with thorough instructions. Start with the Ball Blue Book. https://www.amazon.com/Ball-Blue-Book-Guide-Preserving/dp/B00OEJZSNW

Other Ball books as you progress:
The Ball Complete Book of Home Preserving
The All New Ball Book of Canning Basics

For a full list of places to learn safe canning practices and recipes, look here: https://www.healthycanning.com/learning-resources-for-home-canning

If a cookbook with canning recipes says all the recipes have been tested, you can probably trust it. The Joy of Pickling and Putting Up are both in my collection, and I trust their canning advice. I've seen others recommend Food in Jars, but haven't verified that myself.

In terms of blogs, things get murky. There are two sites I'm aware of that are good about publishing safe recipes that have been tested in a lab, both run by experienced canners.

Food In Jars: https://foodinjars.com/about-food-in-jars/
Healthy Canning: https://healthycanning.com/ 

In the U.S., Extension offices offer a Master Food Preserver program to thoroughly train people on the latest scientific methods and standards in canning. Other than published, tested recipes, they are the people you should get their advice from. I may take the WI course someday.

Beyond water bath canning, pressure canning expands the options for what can be preserved and allows for more creativity within established guidelines. However, it requires special equipment and even more canning. I water bath canned for 5+ yrs before I started pressure canning.

I'm excited to see more people interested in food preservation. Preserving your own food is healthy, satisfying, and delicious. Canning isn't the only way; you can freeze, dehydrate, ferment, etc.

But please do it safely.